1. Field of the Invention
The invention relates to a method for non-destructive temporary marking of zirconium, hafnium, and titanium.
2. The Prior Art
In manufacturing processes, it is often desirable to monitor the location and status of parts. To simplify such monitoring, parts are often marked in some manner. The prior art includes marking systems of three basic types, each of which may have advantages in a particular application. Marking systems requiring mechanical removal of material from the part or substantial disturbance of the material surface are well known. Such methods include engraving, stamping, scribing, and vibratory upsetting. In other applications burning or melting of a portion of the metal, which results in a discernable mark resulting from the altered surface texture, may be employed.
The foregoing methods frequently provide an adequate marking system. Each method provides a clearly discernable mark. Each method also, however, creates an altered metallurgical condition involving a dimensional change, which may be significant and adverse in some applications.
Alternatively, staining, painting or the like may be used to mark items. Use of stencils and painting, for example, provides an inexpensive, flexible, and thoroughly adequate marking system for many applications. Staining, painting, and the like however, contaminate the marked surface.
In some applications the dimensional change or contamination caused by one or more of the marking systems discussed above is unacceptable. For example, in some applications, during construction of military or other aircraft engines it is sometimes desirable to mark parts with identifying numbers and other information without disturbing the surface of the metal. Precision superficial marking without disturbing the metallurgical condition of the metal is also sometimes desirable in the nuclear energy industry. None of the marking systems described above meets these critical requirements.
Applications in the nuclear power industry, and in high performance aircraft, make extensive use of zirconium, alloys of zirconium, titanium, alloys of titanium; hafnium and alloys of hafnium.
Therefore, a need exists for a non-destructive superficial marking system that will not significantly disturb the surface or metallurgical characteristics of a metal workpiece comprising zirconium, titanium or hafnium.